This invention relates to the operation of a gasifier. More particularly, it relates to a method and apparatus for preheating and deslagging a free-flow vertical gas generator for the production of raw synthesis gas, reducing gas, or fuel gas by the partial oxidation of an ash-containing solid carbonaceous fuel or a high-metal-containing liquid hydrocarbonaceous fuel.
Our future energy needs will be satisfied by increased amounts of the less desirable ash-containing solid carbonaceous fuels and heavy liquid hydrocarbonaceous fuels containing organo-metallic impurities. These comparatively low cost materials are attractive alternatives for light naphtha and natural gas which have risen substantially in price in recent years.
A free-flow vertical cylindrical steel pressure vessel lined on the inside with a thermal resistant refractory material is commonly used as the gasifier in the partial oxidation process for the production of raw synthesis gas, reducing gas, and fuel gas. Reference is made for example to coassigned U.S. Pat. Nos. 2,818,326; 4,218,423; and 4,312,637; which are incorporated herein by reference.
Ash-containing solid carbonaceous fuels e.g. coal, lignite, oil shale, tar sands; and liquid hydrocarbonaceous fuels containing a comparatively high amount of metal constituents have been used as fuel in the partial oxidation process for the production of synthesis gas, reducing gas, and fuel gas. Reference is made for example to coassigned U.S. Pat. Nos. 3,544,291; 3,976,442; and 3,996,026.
The hot raw gas stream leaving the reaction zone of the gas generator for the partial oxidation of ash-containing solid carbonaceous fuel or a high-metal containing liquid hydrocarbonaceous fuel contain entrained particulate matter e.g. ash, slag, char, and soot. The temperature of the raw effluent gas stream is in the range of about 1700.degree. to 3000.degree. F. When the gasifier is operated at a temperature above the ash and slag softening point e.g. above about 2200.degree. F., a layer comprising portions of the slag and other entrained matter remains on the inside wall of the refractory after plant shutdown. This layer may cause considerable problems including thermal shock to the refractory at start-up due to low preheat temperatures, and blockage of the gas outlet at the bottom of the reaction zone, if the preheat temperature exceeds the ash fusion temperature.
These problems and others are avoided by the subject invention providing an improved method and apparatus for preheating and deslagging a partial oxidation gas generator.